1. Field of the Invention
The present invention relates to a liquid discharge head and a manufacturing method thereof, and more particularly to a technique of using a deposition method in the manufacture of a liquid discharge head.
2. Description of the Related Art
Recently, in the field of the micro electrical mechanical systems (MEMS), it is considered that the devices using piezoelectric ceramics, such as sensors and actuators, have reached a higher level of integration and these elements are fabricated by a film formation that is suitable for practical use. As a case in point, an aerosol deposition method is known as a deposition technique for ceramics, a metal, or the like. In the aerosol deposition method, aerosol is made from powder of raw material, the aerosol is sprayed onto a substrate, and a film is formed on the substrate by deposition of the powdered material due to its impact energy.
When an inkjet head or another such liquid discharge head is manufactured, the main target product formed by the aerosol deposition method is a piezoelectric member for driving a diaphragm. Japanese Patent Application Publication No. 2003-136714 suggests a method for manufacturing a liquid discharge head wherein a diaphragm made from a metal oxide material is formed on a substrate made from a corrosion-resistant metal material according to the aerosol deposition method. In the manufacturing, after the diaphragm is formed on the substrate according to the aerosol deposition method, the portions of the substrate that server as ink liquid chambers (pressure chambers) are removed by etching, so that the substrate forms pressure chamber dividing walls.
In general, the diaphragms and the pressure chamber dividing walls in the inkjet head are affixed together by adhesive. On the other hand, the method suggested in Japanese Patent Application Publication No. 2003-136714 has merits that there is no need for an adhesion step for affixing the diaphragms with the pressure chamber dividing walls, because the diaphragms are formed according to the aerosol deposition method on the substrate that serves as the pressure chamber dividing walls.
However, in the manufacturing method suggested in Japanese Patent Application Publication No. 2003-136714, since the substrate is etched to form the pressure chambers after the diaphragms are formed according to the aerosol deposition method, the pressure chamber dividing walls are made from a single composition material (e.g., a corrosion-resistant metal material). There are also restrictions that the corrosion-resistant metal material substrate must be an etchable material, and the diaphragms formed according to the aerosol deposition method must be made of a non-etchable material. There is no conventional technique in which the pressure chamber dividing walls are formed according to the aerosol deposition method.
When there is a large difference in the composition material between the pressure chamber dividing wall and the diaphragm, there is a problem that the affinity between the pressure chamber dividing wall and the diaphragm given by the aerosol deposition method inclines to decrease. Moreover, since air bubbles are likely to remain in the corner sections of the pressure chamber, it is preferable that the pressure chamber dividing walls and others are liquid-philic.
In the present specification, the term “liquid-philic” means “having a strong affinity for the liquid (e.g., the ink in the inkjet head)”. For example, in the case where the liquid or the ink is an aqueous solution or water-based, the terms “liquid-philic” and “liquid-philicity” correspond to “hydrophilic” and “hydrophilicity”, respectively. On the other hand, in the case where the liquid or the ink is an oleaginous solution or oil-based, the term “liquid-philic” and “liquid-philicity” correspond to “oleophilic” and “oleophilicity”.
Furthermore, in the inkjet head, since the capacity of the pressure chamber is changed by deforming the diaphragm so as to discharge the ink from the pressure chamber through the nozzle and to fill the ink into the pressure chamber, it is then preferable that the pressure chamber dividing wall has high rigidity to increase the torque in discharging ink.
As mentioned above, the pressure chamber dividing wall requires corrosion resistance, affinity to the diaphragm through the aerosol deposition method, liquid-philicity, and high rigidity. There are hence problems that the pressure chamber dividing wall allows little flexibility in the material design and has not been adequate for the requirements.